The present invention relates to a process and a device for the management of road traffic using the video camera as information source.
Measurement, regulation and monitoring are the principal tasks in traffic management.
Known as measurement devices are magnetic or inductive loops which are embedded in the roadway. These magnetic loops are formed of insulated copper wire coils of various sections creating a transducer that is sensitive to the presence of the metallic mass of a vehicle in its magnetic field. The sensitivity of the device is defined by the relative variation of the inductance upon passage of the vehicle over the loop and allows its detection. Said magnetic loops require grooving of the pavement for their definitive installation and maintenance. This type of operation is tedious and costly; it does not allow for upgrading nor leave room for any error. The surface tracking zone is relatively small. Installation requires interrupting traffic. All of the measurements derived from the identification of vehicular passage are punctual. The coverage of the surface by the vehicles cannot be evaluated. In the case of a waiting line of vehicles, the lack of vehicular presence over a magnetic loop does not enable identification of said waiting line. Neither pedestrians nor two-wheel vehicles are identified. The measurement is blind. The life expectancy of the magnetic loops is directly dependent on the state of the traffic and the roadway. Magnetic loops do not allow for self-diagnostics.
Known as measurement devices are pneumatic tubes which are in the form of rubber tubes. They are attached to the roadway perpendicular to the flow of traffic. Passage of the wheels of a vehicle causes a punctual compression which creates a pressure change inside the tube which is propagated to the ends so as to actuate an electric information identification contact. The vehicles are counted based on the number of pairs of wheels. These pneumatic tubes do not allow identification of multiple lanes of traffic nor can they distinguish trucks, two-wheel vehicles or pedestrians. The surface tracking zone is relatively small. All of the measurements derived from the identification of vehicular passage are punctual. The coverage of the surface by the vehicles cannot be evaluated. In the case of a waiting line of vehicles, the lack of vehicular presence over the pneumatic tube sensor does not enable identification of said waiting line. The measurement is blind. These pneumatic tubes are fragile and their life expectancy is very directly linked to the quality of the rubber, to the traffic and vandalism; it can range from several days to several months.
Known as measurement devices are piezoelectric sensors which are coaxial shielded cables constituted by a core and a copper sheath which are insulated from each other by a piezoelectric ceramic. Prior to their insertion in the roadway, these sensors must be packaged in a resin bar, the length of which corresponds to the width of the roadway. The weight of a vehicle creates a pressure variation which allows identification. Installation requires a specialized staff and traffic must be stopped for several hours. These piezoelectric sensors are sensitive to the mechanical stresses created by the pressure of the vehicles""wheels in the upper layer of the roadway. The installation must be maintained in accordance with very strict guidelines (the roadway must at all times be sound, clean and intact). The surface tracking zone is relatively small. All of the measurements derived from the identification of vehicular passage are punctual. The coverage of the surface by the vehicles cannot be evaluated. In the case of a waiting line of vehicles, the lack of vehicular presence over the piezoelectric sensor does not enable identification of said waiting line. The measurement is blind. Piezoelectric sensors do not allow for self-diagnostics.
Known as measurement devices are radar and ultrasonic sensors which identify a vehicle by the reflection of an emitted wave. The backscattered wave returns with a frequency shift that allows identification of the direction and the speed of the moving object. The surface tracking zone is relatively small. All of the measurements derived from the identification of vehicular passage are punctual. The coverage of the surface by the vehicles cannot be evaluated. In the case of a waiting line of vehicles, the lack of vehicular presence in the wave field does not enable identification of said waiting line. The measurement is blind.
Known as measurement devices are magnetic sensors which operate by means of an analysis of the variation of the magnetic field of the ground induced by passage of a vehicle. The surface tracking zone is relatively small. All of the measurements derived from the identification of vehicular passage are punctual. The coverage of the surface by the vehicles cannot be evaluated. In the case of a waiting line of vehicles, the lack of vehicular presence on the sensor does not enable identification of said waiting line. The measurement is blind.
Known as measurement devices are video sensors which identify the passage of a vehicle by means of an analysis of the variation in lighting on predefined lines. The surface tracking zone is relatively small. All of the measurements derived from the identification of vehicular passage are punctual. The coverage of the surface by the vehicles is not evaluated.
Regulation of road traffic by means of the signaling of three-color traffic lights comprises using a control unit, called an intersection controller, to control the changes in state of the signals and the duration of the states at the predictable or random demand of the group of users. Certain controllers schedule the green-light time in a cyclical and definitive manner. They do not take into account the demand. Certain controllers schedule the green light signal according to a signaling program selected in relation to the day and time. The signaling program""s are contained in memory in a library of programs that have been previously calculated in relation to the traffic measured by magnetic loop type sensors or by direction counting surveys performed manually by monitors. The traffic variations are of two types: the regular predictable variations and the exceptional and random variations. These latter variations can be notable from one day to the next for the same hourly period. Certain controllers are capable of evaluating these variations from the consequences that they generate several minutes later based on the installation of magnetic loops at the entries and exits of each intersection to be regulated. The measurements employed stem from sensors whose surface tracking zone is relatively small. The lack of spatial information means that all of these regulation systems remain blind, such that they are unable to take into account the local and temporal details that influence the congestion and the spatial capacity of the intersection, section and road network. Collection of data based on the flow rate does not allow detection of the regulation and traffic circulation disturbances. Certain cities install cameras in the so-called critical traffic circulation intersections for manual monitoring of the road traffic to supplement information stemming from magnetic loops installed under the road surfaces. Congestion indicators are displayed on a control light panel to attract the attention of the traffic technician who interrupts his tasks in process in order to select the camera corresponding to the intersection and control the display of the images in order to diagnose the type of traffic situation and to manually actuate the controller of the intersection in question.
Video monitoring devices are known which comprise a series of cameras linked to a display panel which has a series of display screens enabling an operator to monitor a certain number of sites entering in the cameras""fields. Such a device allows a single operator to perform monitoring of a large number of sites, such that the number of monitored sites can be larger than the number of display screens. The role of the operator is to monitor the various traffic disturbances so as to be able to act on the controllers of the three-color traffic light signals. The cameras allow the operator to understand the traffic phenomena. The video is received at the central station of the streets department over special cables (fiber optic or coaxial cables). Video recorders continuously record the traffic so as to allow, in the case of problems, the redisplay of the cassette for identification.
This type of monitoring is very tedious and costly, particularly when the events being monitored occur at a low frequency and the operator""s attention is therefore seldom required. This type of disturbance monitoring is not automated with regard to identification and making a regulation decision. In addition, a display of this type does not allow retrospective monitoring of the unfolding of the events in the case of a traffic disturbance. Specifically, in the case of accident, formation of waiting lines, rapid creation of traffic jams, gridlock, going through red lights, increased pollution or increased nuisance, it is not possible to reconstruct with certainty the circumstances that led to the disturbance.
Each traffic management task has these devices available. The use of the camera is limited to human observation purposes by an operator of the traffic operations.
A goal of the device and process of the invention is improvement of the traffic management by including the camera as information source and automating the extraction of the useful information by image processing and analysis techniques performed on the video images of the traffic and circulation. The improvement of the traffic management begins by:
Automatically measuring the road traffic movements.
Automatically diagnosing the regulation operation and its deficiencies.
Remotely controlling the three-color traffic signals by automatically taking into account the spatiotemporal information (vehicular surface coverage in time) on the road traffic movement stemming from the devices of the invention.
Automatically monitoring the events and their origins that could be relevant to the traffic manager.
In order to achieve this goal, it is provided according to the invention for the integration of the device on site for measurement and diagnostics, for regulation and monitoring by using in a general manner the images from the cameras installed in the site in question and using the information relative to the operating of one or more intersection traffic lights.
A goal of the present invention is to resolve the shortcomings, as cited in the introduction, of the presently available devices and to provide multiple advantages such as:
In measurement and diagnostics:
The identification of the passage of a vehicle yields punctual information so as to have compatibility with the present measurements and spatiotemporal information linked to the roadway surface occupied by the vehicle.
The new spatiotemporal measurements make it possible to obtain new magnitudes of the road traffic for evaluation, for example, of the waiting lines, traffic jams and gridlock.
The measurement and diagnostic zones are not fixed.
The lack of a requirement for civil engineering to define the measurement and diagnostic zones.
The process allows identification of all types of movement such that pedestrians as well as two-wheel vehicles can be identified.
Everything measured in the video scene is visible; thus, the measurement is not blind.
Reduction in grooving.
Reduction in inconvenience for users.
Maintenance is easy.
Automation of all types of counting including directional counting so as to obtain the origin-destination matrix which is useful for the regulation of the three-color traffic lights.
Evaluation of the efficacy of regulation strategies.
In regulation:
Regulation taking into account the surface coverage so as to optimize the capacity of the road network.
Take into account the instantaneous demand of the traffic.
Take into account the movements in the center of the intersection and in all zones seen by the camera.
Take into account turning movements.
Facilitate the development of regulation strategies according to the objectives of the manager.
Simulate and validate the strategy prior to its on-site implementation.
Better manage the congestion.
Reduce the costs of traffic regulation.
In monitoring:
Parameterization and definitions of the events.
Automatic identification of the events.
Storage in memory of the origin and beginning of noteworthy events.
Maintenance of traffic.
Lack of consumables.
Remote transfer of the events.